Warp knitting machine with threadseparating means



Aug. 17, 1954 K. LIEBRANDT ET AL WARP KNITTING MACHINE WITH THREAD-SEPARATING MEANS Filed Sept. 4, 1953 Patented Aug. 17, 1954 UNITED STATES PATENT OFFICE WARP KNITTING MACHINE WITH THREAD- SEPARATING MEANS Application September 4, 1953, Serial No. 378,588

Claims priority, application Germany September 20, 1952 3 Claims.

Our invention relates to warp knitting machines and more particularly to machines in which the threads, passing from the warp supply beams or spools to the knitting tools, are kept under tension by means of a tensioning bar that extends across the parallel thread paths between the thread source and the tools. The tensioning bar is elastically urged away from the tools so that the threads are tensioned between the bar and the tools in accordance with the desired loop size and density of the knitted product.

It is desirable and known to pass the warp threads through a guide comb before they enter onto the tensioning bar. Such a comb comprises a large number of thin pins that straddle the individual threads so that the threads will run onto the tensioning bar in an orderly fashion and properly spaced from each other thus being prevented from crossing each other or becoming otherwise entangled and twisted.

As a rule, the thread guiding comb has been rigidly mounted on the stationary frame structure of the machine ahead of the tensioning bar. This obstructs the space at a location where only little clearance is available so that it is difficult to manipulate the threads during threading and similar operations.

The tensioning bar in warp knitting machines has its two ends mounted on spring biased supports, and it has also become known to mount a thread guiding comb on these supports or directly upon the tensioning bar. According to these designs, the individual spacer pins of the comb are secured in a leaden bar, or they are mounted on a comb rail that is attached as a separate part to i the tensioning bar. Both designs have the considerable disadvantage of essentially increasing the Weight of the tensioning bar. The tensioning bar, however, must be capable of moving upwardly and downwardly at high speed if fine threads are to be fabricated at a high operating speed, and such a rapid operation can not be satisfactorily secured with designs that increase the weight and mass of the movable tensioning structure. For that reason, the above-mentioned thread guiding combs have been used only in cases where their use was indispensable, despite the fact that a good guidance of the threads from the warp supply to the knitting tools is always desirable for producing goods of better quality.

It is an object of our invention to eliminate the above-mentioned disadvantages and to aiford an operation with properly guided warp threads under all operating conditions and without appreciably reducing the limited space available near the tensionin bar.

To this end, and in accordance with my invention, the thread tensioning bar between the thread source and the knitting tools is directly designed as the carrier of the individual spacer pins that, in totality, form the thread guiding comb. According to a more specific feature of the invention, the tensioning bar is formed of sheet metal and has a part-tubular portion whose outer surface is engaged by the threads. To permit mounting the individual spacer pins in a simple and weight-saving manner, the sheet metal structure of the bar has a longitudinal fold into which the pins are inserted. The pins may be firmly secured in the fold, for instance, by pourable or kneadable substance or cement which, after being applied, becomes hardened and solidified, although it is also possible to firmly secure the pins on the tensioning bar by clamping, screwing or the like.

A particular advantageous design of a combined thread tensioning and thread spacing bar is shown by way of example on the drawing, in which:

Fig. 1 shows a part-sectional side view of a tensioning device in a warp knitting machine according to the invention, Fig. 2 is a partial front view of part of the machine, and Fig. 3 shows separately and on a larger scale a pertaining thread-tensioning bar.

In the illustrated machine, the warp threads I to be knitted pass from a warp beam 2 over the curved surface of a thread tensioning bar 3 to the knitting tools t. The machine has a large number of tools disposed in a row extending horizontally, i. e. perpendicularly to the plane of illustration of Fig. 1. The tensioning bar 3 is common to all warp threads and for that reason extends horizontally along the length of the machine as is apparent from Fig. 2. The guide bar 3 is carried on two arms 5 which are firmly mounted on a cross shaft 6. Each arm is provided with a leaf spring 1.

The cross shaft 6 is rotatably adjustable to lift or lower the tensioning bar 3. The adjustment is controlled by a control shaft 8'. An abutment lever 9 is firmly mounted on control shaft 8 and carries a roller It resting upon the top face of the leaf spring 7 so that the leaf spring is kept in force-constrained engagement with the abutment lever. Firmly mounted on one end of control shaft 8 is an adjusting segment H with whose aid the control shaft can be set to a desired angular position in accordance with the desired tension of the thread. A manually operable set screw l3 serves to clamp the segment II in the chosen position relative to the machine frame I2.

When turning the control shaft 8 with the aid of the segment II, the abutment point at which the leaf spring I rests against the roller of the abutment lever 9 is shifted toward or away from the cross shaft 6. As a result, the cross shaft is turned accordingly, thus shifting the tensioning bar 3 as needed for obtaining the desired thread tension.

For each loop-forming operation of the knitting needles 4 a certain amount of yarn is payed out from the beam 2 Whose movement is frictionally or otherwise impeded. Hence, the consumption of thread during each course of operation of the knitting tools 4 acts upon a limited length of thread between the beam and the tools. As a result, the tensioning bar 3 is pulled downward in opposition to the spring bias of the leaf springs. Thus, the thread is subjected to a tension whose magnitude depends upon the elastic force offered by the leaf springs, and this force is determined by the effective spring length and hence by the adjusted position of the spring abutment points at which the springs rest against the rollers or abutment faces of the control shaft.

The tensioning bar 3 consists of an elongated structure of sheet metal and has a portion which is circularly bent downwardly so as to form a substantially semi-tubular shape. The smooth peripheral exterior surface of the curved portion is engaged by the individual threads. The sheet metal structure is further provided with a fold 15 that extends along the curved portion. A large number of individual spacer pins H; are inserted into the fold 15. The pins may be fastened in the fold merely by clamping action. However, to secure a firm connection, a pourable or kneadable cementing mass [1 is applied which hardens after its application.

It will be recognized that the addition of the comb pins does not appreciably increase the weight of the tensioning bar and hence does not have a noticeable effect upon the operation of the machine. The necessity for threading the warp through separate spacer combs is eliminated and the threading-in operation facilitated.

It will be understood that the invention permits of various modifications. For instance, the particular design of the elastic means and adjusting means associated with the tensioning bar may be given any suitable design other than that exemplified on the drawing and the foregoing description. The particular tensioning and tension-adjusting device above-described as an example is in accordance with the copending application of Arno Zwingenberger, Serial No. 328,850, filed December 31, 1952, entitled Thread Tensioning Device for Warp Knitting Machines.

We claim:

1. In a warp knitting machine having warp thread suppl means and knitting tools, the combination of a resiliently yieldable elongated thread-tensioning bar, said tensioning bar comprising an integrally formed smooth longitudinal curved surface portion adapted for sliding guidance of the warp threads thereover in their passage from said supply means to said tool means, and thread separating comb means having a multiplicity of parallel outwardly-extending spacer pins individually mounted on and along said tensioning bar.

2. In a warp knitting machine according to claim 1, said tensioning bar being fabricated of sheet metal and having a longitudinal double-bent portion forming a bight within which spacer pins are fastened.

3. In a warp knitting machine having warp thread supply means and knitting tools, the combination of a resiliently yieldable thread-tensioning bar engageable by the warp threads passing from said supply means to said tool means, said tensioning bar consisting essentially of a sheet metal structure having an approximately semitubular portion whose outer peripheral face is engaged by the warp threads when in operation and extends across the paths of the threads, said structure having a fold extending longitudinally in parallel relation to said thread-engaged portion, and a multiplicity of parallel outwardly-extending spacer pins secured in said fold.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,308,430 Bolden et a1 Jan. 12, 1943 2,442,796 Young June 8, 1948 

